Many growers overlook the huge importance of CO2 to fast growing
plants. CO2, along with light, are the two most important
sources of food for plants. Plants take light and CO2, and
through a process called photosynthesis, produce food for
themselves. The nutrients that growers feed their plants are
kind of like the salt and pepper, whereas the light and CO2
are like the meat and potatoes. The nutrients are necessary
for photosynthesis to occur, but they are mainly a catalyst
to allow the reactions to take place. In fact, if you were
to analyze any plant, you would find that it consists of over
90 percent water, a few percent nutrients, and the rest is
carbon.

Normal
CO2 levels are between 300 to 500ppm (parts per million),
depending on whether you live in an urban or rural area (we
have almost 600ppm of CO2 here in Los Angeles!). Increasing
these levels to 1500ppm can often have dramatic effects on
your plants, including faster growth rates and increased yields.
This is why it is so important to always have fresh air circulating
into your grow room, or better yet, add supplemental CO2.

.

What
are the most common ways of adding CO2?

The two most common devices used to produce CO2 are CO2 generators
and bottled CO2.

Bottled
CO2:

Bottled
CO2 is perfect for small areas up to around 12' x 12' x 8'.
CO2 tanks are available in several different sizes, but the
two most common sizes used for enriching grow rooms are 20#
and 50#. When full, a 50# tank weighs a considerable amount;
even a very strong person will need a dolly to transport it.
CO2 tanks can be filled at most welding and dry ice companies.
Keep in mind before you bring your shiny new tank to a welding
company that many of them will exchange your empty tank for
a used full one rather than filling it up, so make sure to
ask first. Most places will charge less than $20 to fill a
20# tank and $50 for a 50#. In addition to the CO2 tank, you
will also need to purchase a CO2 Enrichment System to properly
dispense the CO2. The enrichment system attaches directly
to the CO2 tank with either a wrench or channel locks. Most
enrichment systems consist of a pressure regulator and gauge,
a solenoid valve, and a flow meter. The flow meter allows
you to adjust the amount of CO2 coming out of the tank, and
the solenoid valve allows you to attach a timer or other device
to turn on and off the flow of CO2, thereby maintaining the
desired level of CO2 (usually between 1500 and 2000ppm).

CO2
Generators:

CO2
Generators are generally a little more expensive than CO2
tanks and also produce a small amount of heat, but they offer
several advantages. Generators operate on either propane or
natural gas, both of which are less expensive and easier to
come by than bottled CO2. Propane generators can operate using
just about any propane tank, including the small ones used
for barbeque grills. Some growers use the natural gas hookup
provided for a gas dryer in their house to attach natural
gas generator, which not only saves the labor of swapping
out empty propane tanks, but also saves them money, as natural
gas is much cheaper than propane. Some generators, such as
the MegaGrowth, are vented so that you can attach an exhaust
fan and eliminate some of the heat they produce.

Regardless
of which solution you choose (bottled CO2 and an enrichment
system or a CO2 generator), you will still need something
to control it. Keep reading for information on how to accomplish
this.

.....

When
and how often do I need to use CO2?

C02
should only be used when your lights are on, as plants only
use CO2 during photosynthesis. C02 is most effective during
the flowering stage, but BGH recommends using CO2 throughout
the life of your plants for maximum results.

..............

How
do I keep my room from getting too hot?

Heat buildup in a grow room is a common problem among growers.
We usually advise our customers not to go crazy and spend lots
of money from the get go, but instead take it in stages. Start
with the cheapest and simplest solutions first and graduate
to more expensive and complicated one's if the problem persists.
Proper planning of the grow room can make things a lot easier.
Make sure that you have not only installed an adequate exhaust
fan, but also make sure you have sufficient intake, otherwise
your fan will not be able to do its job properly. In most cases,
you will not need to use a fan for the intake, an adequate size
opening in the room will do.

The
next step towards cooling your room is to cool your lights.
Most of the lighting systems and reflectors we carry have
air-cooling options that allow you to hookup your exhaust
fan directly to your reflector, eliminating the heat right
at the source. Almost all air-cooled reflectors have to two
vent openings. Many growers will simply attach their exhaust
fan to one of the ducts with some duct hose so that the hot,
stale air in the grow room will be sucked out along with the
hot air in the reflector that is generated by the bulb. If
you are using CO2, then you will want to suck air from an
outside source, through the reflector, and back outside again
so that you do not suck out any of the CO2-rich air from the
grow room. This scenario also applies if you end up having
to use an air conditioner, since you don't want to suck out
the cool, air conditioned air. Most air conditioners have
a vent which you will want to close so that it recirculates
the air in the room instead of constantly sucking in air from
the outside, especially if the air outside is hot.

If,
after venting your room and installing an air conditioner,
you still can't get rid of the heat problem, you may need
to consider water-cooling your lights. See the lighting section
for products such as the Hydro Coil Water-Cooling Jacket for
more information on water-cooling.

............

What
is the ideal temperature range for plants?

Air
temperature within the grow room should be between 77 and
83 degrees Fahrenheit. Water temperature should be between
68 and 72 degrees Fahrenheit.

................

What
size fan do I need to vent my room?

Due
to the many variables that have to be considered, there is
no exact answer or formula available to determine the fan
size. But, we will at least try narrow things down as much
as possible so that you can make an educated guess. The old
rule of thumb is to try to replace the volume of air in your
room at least once every 5 minutes. Based on years of experience,
BGH feels that you should try to replace it every 1 to 3 minutes
if you are trying to cool your room as well as vent it. The
formula used to determine the volume of your room in cubic
feet is to multiply length x width x height, so a 10
x 10 x 8 room would be 800 CF. Divide this number
by 5 and you will have the minimum CFM (cubic feet per minute)
fan required to vent your room (in this example  160
CFM).